The invention relates to a load-controlled hydraulic actuating arrangement, particularly for a convertible top, according to the species of the claims.
The convertible tops of today are equipped with drive systems that allow a fully automated actuation. For this purpose, motors are arranged for the different single motions of the top in the kinematic system and are controlled via an electronic circuit. This solution has the disadvantage that the load of the motors during the motions cannot be recorded and the motor output cannot be adjusted. The positions of the individual components are sampled for the exact control of the motion sequence via limit switches, and thus a mere sequential run of the motions is generated.
The motion speed of the convertible top can vary in the operating mode due to exterior conditions such as wind from the front or rear side, relative wind or the inclined position of a car to which the convertible top belongs. Undesired approaching speeds of the top parts, e.g. towards the latching units, are the consequence, or it may be necessary to avoid the actuation of the top if the driving speed is too fast. If the top parts collide with objects that are located in the motional path, the resulting increase of the motor output is not identified, resulting in damage to the system.
The patent publication AT 402 280 B describes a hydraulic actuating arrangement for a convertible top with a number of working cylinders that are connected to a common pressure circuit via separate control elements, a control unit that is connected with the control elements and at least one feedback unit that is also connected with the control unit and is used to control the final position of the working cylinders. The feedback unit is provided with at least one pressure sensor in the pressure circuit, and its output signal as a function of time is used together with the defined switching sequences of the single control elements for the final position control of the individual working cylinders.
A system provided with a measuring equipment designed as a rotary potentiometer is described in U.S. Pat. No. 5,225,747. This system can realize the motions not only sequentially, but coherently as a function of a particular motional behavior.
The disadvantage of these two solutions is the fact that the load of the motors during the motion cannot be registered, and therefore, it is not possible to adjust the motor output.